The mass transport and residence time characteristics of ii parallel-plate oscillatory flow reactor have been investigated by studying the reduction of ferricyanide under an array of experimental conditions, including variations in oscillation frequency, oscillation amplitude, net flow rate and flow geometry. Under certain conditions, oscillatory how has been found to give enhancement of mass transport rates in excess of an order of magnitude. The residence time distribution (RTD) response to the injection of an electrochemical tracer has been determined, and results are compared with that predicted by the axial dispersion model.